Hot-Dip Galvanization

Hot-dip galvanization is the process of coating iron and steel with zinc, which alloys with the surface of the base metal when immersing the metal in a bath of molten zinc at a temperature of around 450 °C. When exposed to the atmosphere, the pure zinc (Zn) reacts with oxygen to form zinc oxide, which further reacts with carbon dioxide to form zinc carbonate (ZnCO3), a usually dull grey, fairly strong material that protects the steel underneath from further corrosioni n many circumstances. Galvanized steel is widely used in applications where corrosion resistance is needed without the cost of stainless steel and is considered superior in terms of cost and life-cycle.

Black oxide or blackening is a conversion coating for ferrous materials, stainless steel, copper and copper based alloys, zinc, powdered metals, and silver solder. It is used to add mild corrosion resistance, for appearance, and to minimize light reflection. To achieve maximal corrosion resistance the black oxide must be impregnated with oil or wax. One of its advantages over other coatings is its minimal buildup.

Zinc Electroplating provides corrosion resistance by acting as a barrier and sacrificial coating. Because zinc is more reactive that steel, the zinc coating corrodes first, protecting the steel substrate. The rate of corrosion of zinc is atleast 10 times slower than that of steel, thus a thin coating of zinc can protect steel for long time